Cover tape for packaging electronic components

Abstract

A cover tape for packaging electronic components, which can prevent troubles associated with the peeling strength or trouble appearing during mounting of the electronic components, which can be produced at a low cost, and which is transparent; that is, a cover tape has a peeling strength not too high and not too low and small in difference between the maximum value and the minimum value and which has high transparency. Specifically, the cover tape for packaging electronic components, which can be heat-sealed to a plastic-made carrier tape having pockets capable of storing electronic components, formed regularly therein and which is made of (A) a biaxially oriented film layer made of polyester, a polypropylene or a nylon and (B) a thermoplastic resin layer composed of 100 parts by weight of an ethylene copolymer and 10 to 100 parts by weight of polystyrene, laminated to one side of the layer A.

What is claimed is:  
     
       1. A cover tape for packaging electronic components, which can be heat-sealed to a plastic-made carrier tape having pockets capable of storing electronic components, formed regularly therein and which comprises a layer (A) of a biaxially oriented film layer made of a member selected from the group consisting of polyester, polypropylene and nylon and a layer (B) of a thermoplastic resin layer composed of 100 parts by weight of an ethylene copolymer and 10 to 100 parts by weight of a polystyrene, laminated to one side of the layer A, based on the total weight of the thermoplastic resin layer, wherein the proportion of a comonomer of the ethylene copolymer contained in the layer B is 17 to 90 parts by weight relative to 100 parts by weight of ethylene. 
     
     
       2. A cover tape for packaging electronic components according to  claim 1 , wherein at least one kind of layer selected from the group consisting of a non-oriented polyester layer, a non-oriented nylon layer and a non-oriented polypropylene layer is interposed between the layer A and the layer B. 
     
     
       3. A cover tape for packaging electronic components according to  claim 1  or  2 , wherein a comonomer of the ethylene copolymer contained in the layer B is at least one kind selected from the group consisting of vinyl acetate, acrylic acid, an acrylic acid ester, methacrylic acid, a methacrylic acid ester and an ionomer. 
     
     
       4. A cover tape for packaging electronic components according to  claim 1  or  2 , wherein the layer B has a thickness of 0.5 to 50 μm. 
     
     
       5. A cover tape for packaging electronic components according to  claim 1  or  2 , wherein the layer B gives rise to cohesive failure and peeling when the cover tape is heat-sealed to the carrier tape and then is peeled from the carrier tape. 
     
     
       6. A cover tape for packaging electronic components according to  claim 1  or  2 , wherein an electrically conductive powder made of tin oxide, zinc oxide, titanium oxide, carbon black or a combination thereof and/or a surfactant is dispersed in the layer B and the layer B has a surface resistivity of 1×10 13 Ω/□ or less. 
     
     
       7. A cover tape for packaging electronic components according to  claim 1  or  2 , wherein an antistatic layer which has dispersed therein an electrically conductive powder made of tin oxide, zinc oxide, titanium oxide, carbon black or a combination thereof and/or a surfactant, is formed on the surface of the layer B and the antistatic layer has a surface resistivity of 1×10 13 Ω/□ or less. 
     
     
       8. A cover tape for packaging electronic components according to  claim 1  or  2 , which has a peeling strength of 0.1 to 1.3 N per mm of the sealed width of the cover tape, when the cover tape is heat-sealed to the carrier tape and then peeled from the carrier tape. 
     
     
       9. A cover tape for packaging electronic components according to  claim 1  or  2 , which has a luminous transmittance of 70% or more and a haze of 80% or less. 
     
     
       10. A cover tape for packaging electronic components according to  claim 1  or  2 , which has a difference between the maximum value and the minimum value in peeling strength, of 0.01 to 0.4 N per mm of the sealed width of the cover tape, when the cover tape is heat-sealed to the carrier tape and then peeled from the carrier tape. 
     
     
       11. A cover tape for packaging electronic components, according to  claim 1  which comprises at least two layers of an adhesive layer and a base layer, the adhesive layer being present on the side of the cover tape heat-sealed to the carrier tape, said two layers being laminated with each other by co-extrusion, and the base layer being a polyester, a nylon or a polypropylene. 
     
     
       12. A cover tape for packaging electronic components according to  claim 11 , wherein the adhesive layer is made of an ethylene-α-olefin copolymer and the α-olefin is vinyl acetate, acrylic acid, an acrylic acid ester, methacrylic acid or a methacrylic acid ester. 
     
     
       13. A cover tape for packaging electronic components, according to  claim 1  which comprises at least three layers of an adhesive layer, an interlayer and a base layer in this order, the adhesive layer being present on the side of the cover tape heat-sealed to the carrier tape, the interlayer and the base layer being laminated with each other by co-extrusion, and the adhesive layer being laminated by gravure coating. 
     
     
       14. A cover tape for packaging electronic components according to  claim 13 , wherein the interlayer is made of an ethylene-α-olefin copolymer and the α-olefin is vinyl acetate, acrylic acid, an acrylic acid ester, methacrylic acid or a methacrylic acid ester. 
     
     
       15. A cover tape for packaging electronic components according to  claim 13  or  14 , wherein the adhesive layer is made of an ethylene-α-olefin copolymer wherein the α-olefin is vinyl acetate, acrylic acid, an acrylic acid ester, methacrylic acid or a methacrylic acid ester, a poly (methacrylic acid ester), a vinyl chloride-vinyl acetate copolymer, a polypropylene chloride or a polyurethane. 
     
     
       16. A cover tape for packaging electronic components according to any of  claims 11  to  14 , which has a luminous transmittance of 70% or more and a haze of 60% or less.